Key Findings from Retrocommissioning a High-Performance Building

KLH coordinated multiple tests and reviewed the functional performance testing data and the building’s environmental trend data to find a solution to improve system performance and operating efficiency, and reduce energy costs. Through this research, KLH identified multiple issues, including a problem with the building pressure—the RTU exhaust fan was only enabled when the outside air damper was open above a minimum position and the building pressure was above the building pressure set-point.

The minimum outside air damper position was set to 10 percent on all RTUs and the power exhaust outside air minimum position was set to 20 percent. This set-point prevented the power exhaust from operating and maintaining an appropriate building pressure. After looking at the building pressure trending, KLH discovered that the building pressure would continually rise throughout the day, until approximately 5:00 p.m., when all of the doors opened as employees exited the building. Because the building envelope was secure and the doors remained closed, the building pressure would rise to the point where doors were difficult to close once opened.

To combat this problem, the outside-air minimum damper position set-point (for the power exhaust system) was lowered to 5 percent on RTU #4 in an effort to see if the power exhaust fan would engage and maintain building pressure. Once the set point was lowered to 5 percent, the rooftop unit immediately began to exhaust air. After this change, the BAS showed the building pressure decreased until the programmed building pressure set-point was attained.

In addition to these findings, the RCx study uncovered other opportunities, which KLH recommended to further improve the building’s energy efficiency. These projects include: carbon dioxide space monitoring and outside air ventilation control, a new control strategy for supply duct static reset, installing an enthalpy economizer control, and implementing a new supply air reset control strategy.

The success of the RCx project shows how to utilize RCx not only as a means of obtaining LEED certification points, but as a foundation for responsible energy management practices. According to Johanning, knowing that the mechanical systems and controls operating the buildings are working in sync—and efficiently—creates peace-of-mind, and RCx is the vehicle to deliver those results. Not only did the Springfield RCx project exceed Johanning’s expectations, it also expedited the funding approval process for some of the recommended corrective actions to further enhance efficiency.

The Springfield RCx project was so successful that the business is planning to conduct RCx studies in selected facilities throughout its commercial office portfolio to further drive down operating costs. RCx is proven to be a smart choice for facility managers and building owners who want to streamline their building’s performance and operations. Doing so can further improve building efficiency, save monthly costs, and ensure happier employees with more comfortable working conditions.

Jerry Schmits is Director of Energy Solutions at Kohrs Lonnemann Heil Engineers. You can reach him at jschmits@klhengrs.com.